The blockchain is a chain of blocks that contain information. This process was originally brought to life in 1991 by the assemble of analysts and was originally intended to time stamp digital documents so that is not possible to backdate them or to temper with them, almost like a notary. But it was mostly undetected until Satoshi Nakamoto used it to create a digital crypto currency, Bit coin. The blockchain is a distributed ledger that is completely opened to anyone.
They have an interesting property.one some data has been recorded inside the blockchain it becomes very difficult to change it.
How does a blockchain work?
Each block contains data, hash algorithm from both current and previous block. Depending on the blockchain type you can have different data stored inside. Blockchain used in Bit Coin deposit the details about transactions in here such as sender, receiver and number of coins.
A block also contains of a hash algorithm. Like a fingertip, It identifies block and its content and it is always distinctive just like fingerprints are. Once you create a block, the hash is being calculated, replacing parts inside the block can produce the change. So in other words, hashes are helpfull when you need to notice changes in blocks. In case that the block fingerprint changes, you will have a new block.
The third part and crucial in some way is the hash algorithm of previous block. By this third part chain is effectively created and that is what makes this process of blockchains so reliable.
How secure is it?
In principle, this openness and transparency is a great way of taking out some of the security problems and some requirements for technology for blockchain base systems. Not everything should be opened for everybody to see. The details about transaction maybe private between two people who did it for many good reasons. So, getting that balance of openness and transparency with other reasonable expectations of privacy and secrecy is very tricky.
Cryptography is going to be very important to this regardless. Compared with modern systems and traditional systems, some of the problems move around, but keeping things safe and information trustworthy remain absolutely as relevant in the blockchain case as they have done in the history of information. It is as secure as it should be, and bright future is within and everyone who follows its path.